This invention relates generally to a system for melting and dispensing a thermoplastic hot melt adhesive.
Hot melt adhesives are used in many applications including laminating of film and nonwoven layers together, the gluing of diaper components, as well as a variety of other applications such as gluing furniture parts together, laminating, and the like. In order to meet the requirements for a diversity of applications, the applicator may be in the form of a hand-held glue gun or a battery of dispensing nozzles. The dispensing nozzles may be in the form of air-assisted meltblowing nozzles, spiral nozzles, bead nozzles, spray nozzles, or combinations of these.
The melting and dispensing apparatus receives the thermoplastic in solid form and melts it in a hopper from which positive displacement pumps deliver the hot melt to the dispensers via hoses and/or manifolds.
Most hot melt systems also include filters for removing foreign particles and char, and safety relief valves for preventing damage to the equipment in the event of down stream failure or plugging.
Hot melt delivery systems are disclosed in the following U.S. Patents: U.S. Pat. No. 4,474,311, U.S. Pat. No. 4,666,066, U.S. Pat. No. 5,061,170, U.S. Pat. No. 5,680,963, U.S. Pat. No. 5,699,938, and U.S. Pat. No. 5,692,884. The hot melt delivery and dispensing systems disclosed in the above U.S. Patents are representative only of a few types that are commercially available.